1. Field of the Invention
The present invention relates to a touch display device, particularly to a touch display device having auxiliary capacitor.
2. Description of the Related Art
General touch display devices have a touch module stacked on a screen, causing the depth thereof not slim enough to meet the market's requirement. Besides, this structure also has room for cost reduction.
To solve the problems, one solution is to make a same material layer shared by the screen and the touch module. However, the resultant depth of the touch display device is still not slim enough to meet the requirement of some high end products.
Another solution is to implement a touch function directly on a display device. Please refer to FIG. 1, which illustrates a prior art touch display device. As illustrated in FIG. 1, the prior art touch display device mainly includes two opposing electrode substrates 14, 15, an interface 21, multiple switches 22, a control unit 24, a signal generator 25, and a signal evaluation circuit 27.
The electrode substrates 14 and 15 each have multiple display electrodes 11, and each of the multiple display electrodes 11 of the electrode substrates 14 opposes one of the multiple display electrodes 11 of the electrode substrates 15.
The interface 21 is used to couple with a conventional display driving controller (not shown in the figure).
The multiple switches 22 are used to connect the electrode substrates 14, 15 with the interface 21 to provide a display function, or with the signal generator 25 to provide a touch function. When the electrode substrates 14, 15 provide the touch function, the signal generator 25 will output a test signal and the signal evaluation circuit 27 will detect a change of the test signal to determine if a touch event occurs.
However, although the active time of the touch function is set to not overlapping with the active time of the display function, the average display brightness thereof will decrease and the display image will tend to have flicker phenomenon (especially when the display device is implemented by OLED (organic light emitting diode) or PLED (polymer light emitting diode), both OLED and PLED requiring electric current to maintain light emitting, the display image will be blacked out when the electric current is interrupted.)
To solve the foregoing problems, a novel touch display device is needed.